/*
 * Copyright (c) 2024 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

class FetchedRegistry {
  private readonly fetchedIndicies: Set<number> = new Set(); // {I where I is in cache} ∩ `prefetchRange`
  private rangeToPrefetch: IndexRange = new IndexRange(0, 0);

  addFetched(index: number): void {
    this.fetchedIndicies.add(index);
  }

  getFetchedInRange(range: IndexRange): void {
    let fetched = 0;
    range.forEachIndex((index) => {
      fetched += this.fetchedIndicies.has(index) ? 1 : 0;
    });
    return fetched;
  }

  updateRangeToPrefetch(prefetchRange: IndexRange): void {
    this.rangeToPrefetch.subtract(prefetchRange).forEachIndex((index) => {
      this.fetchedIndicies.delete(index);
    });
    this.rangeToPrefetch = prefetchRange;
  }
}
